NAME

SYNOPSIS

DESCRIPTION

bdflush() starts, flushes, or tunes the buffer-dirty-flush daemon.
Only a privileged process (one with the CAP_SYS_ADMIN capability) may
call bdflush().
If func is negative or 0, and no daemon has been started, then
bdflush() enters the daemon code and never returns.
If func is 1, some dirty buffers are written to disk.
If func is 2 or more and is even (low bit is 0), then address is the
address of a long word, and the tuning parameter numbered (func-2)/2 is
returned to the caller in that address.
If func is 3 or more and is odd (low bit is 1), then data is a long
word, and the kernel sets tuning parameter numbered (func-3)/2 to that
value.
The set of parameters, their values, and their valid ranges are defined
in the kernel source file fs/buffer.c.

RETURNVALUE

If func is negative or 0 and the daemon successfully starts, bdflush()
never returns. Otherwise, the return value is 0 on success and -1 on
failure, with errno set to indicate the error.

ERRORS

EBUSY An attempt was made to enter the daemon code after another
process has already entered.
EFAULTaddress points outside your accessible address space.
EINVAL An attempt was made to read or write an invalid parameter
number, or to write an invalid value to a parameter.
EPERM Caller does not have the CAP_SYS_ADMIN capability.

CONFORMINGTO

bdflush() is Linux-specific and should not be used in programs intended
to be portable.